
class A:
    title = 'A'
    def PT(self):
        print(self.title)
        pass


class B(A):
    title = 'B'
    def PT(self):
        super().PT()
        print(A.title)
        print(self.title)


def add(a:int,b:int) -> int:
    return a+b

from typing import Union
def add2(a:Union[int,str],b:Union[int,str]) -> Union[int,str]:
    return a+b


app:list = [A(), B()]
app2:list[Union[str,int]] = [1,2,'3']


if __name__ == '__main__':
    b = B()
    b.PT()

